Examples of known mechanically-actuated (i.e., mechanically-driven) fuel injection pumps are shown in U.S. Pat. No. 4,392,612 issued on Jul. 12, 1983 to Deckard et al. and U.S. Pat. No. 4,782,807 issued on Nov. 8, 1988 to Takahashi. Such fuel injection pumps typically include a reciprocal tappet having a bifurcated or forked end portion clasped around a flanged end portion of a fuel pump plunger. An engine drive train (typically including a camshaft, a rocker arm, and perhaps a pushrod) periodically drives the tappet and plunger assembly in a reciprocating motion between a retracted position and a fully-stroked position.
A potentially catastrophic problem may occur with this arrangement if the plunger accidentally becomes seized in its housing bore (which is most likely to occur when the plunger is at or near its fully-stroked position which generates the highest fluid pressure). If the plunger becomes seized, the moving components of the engine drive train will separate from the tappet whose reciprocating motion is immediately stopped or restrained by the seized plunger. Separation of the engine drive train from the tappet can cause catastrophic damage to the engine by misaligned engine drive train components, such as push rods, which become separated from the tappet or other mating components of the engine drive train.
The present invention is directed to overcoming one or more of the problems as set forth above.